Automatic safety switch for vehicles



Jan. '5 1937.

E. D. LAWSON AUTOMATIC SAFETY SWITCH FOR VEHICLES Filed April 18, 1955Patented Jan. 5, 193? LWMS'Z AUTOMATEU SAFETY SWHTCH FQR VEHICLES EdwardD. Lawson, Park Ridge, llli. Application April 18, 1935, Serial No.16,986

9 Claims.

This invention relates to improvements in automatic safety switch forvehicles and it consists of the matters hereinafter described and moreparticularly pointed out in the appended claims.

One of the objects of the invention is to provide a switch for use inconnection with the ignition and other electrical circuits of anautomotive vehicle, and which shall automatically break said circuit orcircuits should the vehicle turn over in any way beyond somepredetermined angle with the-result that all circuits being dead, theengine will stop and the danger of fire from all electrical sources willbe eliminated.

Another object of the invention is to provide a switch of this kindwhich shall be proof against premature operation due to the jarring andjolting that the associated vehicle may receive under extremely adverseroad conditions.

A further object of the invention is to provide a switch which may beshipped with safety to the user and may be applied to a vehicle withoutrequiring adjustments or alterations of any kind before its applicationto said vehicle.

Still another object of the invention is to pro- 5 vide a switch of thiskind including a pair of oppositely diverging mercury tubes andrelatively long associated electrodes, the lower portions of which areso disposed in the mercury of the associated tube as to insure the amplebathing of 30 upper portions of the electrodes with mercury to keep thecircuit closed during the jarring and jolting of the vehicle should thejarring and jolting be severe enough to cause the mercury to rise in itstube.

35 Still a further object of the invention is to provide a switch ofthis kind comprising a pair of inclined mercury tubes and associatedelectrodes, each tube including a surge chamber extension through whichthe electrodes enter the tube, there 40 being associated with each surgechamber, a deflector for directing mercury thereinto and thereby tolimit mercury movement in response to vehicle jarring andjolting, to onewhich cannot break the circuit controlled by the switch,

45 unless the vehicle turns or tips over beyond-some predeterminedangle.

Again, it is an object of the invention to provide an improved cushionmounting for the mercury tubes of the switch so that they will not 50become broken through accident or otherwise.

The above mentioned objects of the invention, as well as others, willmore fully appear as I proceed with my specification.

In the drawing 55 Fig. 1 is a longitudinal vertical sectional view on asomewhat enlarged scale, through a switch made in accordance with oneembodiment of the invention, as taken on the line l-l of Fig. 2.

Fig. 2 is a transverse vertical sectional view through the switch astaken on the line 22 of 5 Fig. 1.

Fig. 3 is a perspective view of one of a pair of cushioning elementsemployed in the switch and which will be referred to in more detaillater.

Referring now in detail to that embodiment of 10 the invention,illustrated in the accompanying drawing 5 indicates, as a whole, thecasing for the switch which is substantially of an inverted triangularshape. Preferably the casing comprises a. body 15 6 of sheet materialand a cover i therefor also preferably of sheet material, the cover andbody having a beaded over marginal flange extension 8. In said flangeextension are openings 9, as indicated in dotted lines-in Fig. 1, toreceive fas- 20 tening devices whereby the switch may be secured inplace upon the associated vehicle. When in place upon the vehicle, theswitch will occupy a vertical position extending transversely of thevehicle.

The interior of the casing is substantially filled by a cushion elementIt that encloses a pair of mercury tubes HH disposed at opposite anglesinclined from the perpendicular. At these angles, said tubes standparallel with the upwardly and oppositely inclined bottom walls of thecasing. Each tube is provided with a substantially perpendicular surgechamber I 2 and in each tube is a quantity of mercury it which, ofcourse, seeks its normal position at the bottom end of each tube as bestappears in Fig. 1.

In each surge chamber is sealed a pair of electrodes l4 and I 5respectively, the bottom ends l4a--l 5a of which are bent to follow theinclination of the tube and to extend into the mercury in the respectivetubes so as to be electrically connected thereby.

The electrodes M and [5 have end portions disposed outside the sealedends of the surge chamber extension and the electrode M of one tube iselectrically connected to the electrode M of the other tube by aflexible conductor l6 such as a piece of stranded wire. The end portionof each electrode l5 has connected thereto one end of a flexibleconductor H, the other end of said conductor being connected to aflexible terminal strip 18. Each terminal strip which is made of a thinsheet metal is secured to an associated terminal post I9 in the form ofa screw that extends up through an associated opening in the horizontaltop wall of the casing body. A lock nut 20 secures each screw in placeand also on each screw is a clamp nut 2| whereby a conductor 22 may beattached, said conductors forming a part of the circuit to becontrolled.

Each tube and its surge extension chamber is evacuated and preferablyfilled with an inert gas, thereby eliminating the possibility ofcorrosion of the terminals or electroplating the interior surface of thetube with a mercury film that might render the switch inoperative forits intended purpose under certain conditions.

As an added precaution to insure perfect contact under the most abnormaloperating conditions as when the vehicle is subjected to severe andunusual jolting, means are provided to defiect and momentarily trap themoving mercury in the surge chamber. Such means comprises a defiectormember 23 fixed to each electrode l5 near its bent bottom end I5a.

When the jolting the vehicle receives is of such magnitude as to causethe mercury in either tube to move or surge upwardly therein, themercury will engage the associated deflector and will be deflected orturned into the adjacent surge chamber. This action assures constantsubmersion of the conductors in the mercury under all-operatingconditions no matter how active and agitated the mercury may become. Anymercury entering the surge chamber in this manner, of course,automatically returns to its well at the bottom of the associated tube,bathing the electrodes with mercury on said return.

The mercury tubes described are cushioned in the casing in a mannerprotecting them against damage due to jolting and the means therefor isas follows- Within the casing so as substantially to fill the same is apair of cushion elements 24-24 composed of a relatively soft rubber. Theconstruction is best shown in perspective in Fig. 3. Each element 24 isprovided in one face, with recesses Ila, Ila, Him and Ha. respectively,which coact to receive the tubes l l, surge chamber extensions l2 andconductors l6 and H respectively, when said elements are arranged withtheir recessed faces engaging each other as best shown in Fig. 2.

In the assembly of the structure described, the tubes and conductors aredisposed in the recesses provided therefor in a pair of cushion elementsarranged face to face. When the tubes are thus disposed, the terminalclips 18 extend up between the top margins of the cushion elements. Withthe parts in this position, they are placed within a casing body withthe screws [9 extending upwardly through the associated openings in thetop wall of the casing body and then the lock nuts 20 are applied.

A cover 1 is then applied and its margins are preferably flanged overthe flange extension of the cover plate. By the application of the coverplate, the cushion elements are very slightly compressed and thisassuresthat they will securely hold the tubes in place and yet protect themagainst damage.

It is pointed out that the conductors 22 preferably form a part of theelectrical system of the vehicle to which the switch is attached. Shouldthe vehicle, through accident, turn over sidewise or endwise, it isapparent that the mercury in one or both tubes will run toward theopposite end of the tube. This will leave the electrode ends bare orfree of mercury so that they are electrically disconnected. Therefore,the circuit of which the conductors form a part, is broken, therebystopping the engine and making all parts electrically dead. Thus shouldfuel be spilled when the vehicle turns over, it will not become ignitedand cause a fire.

When the vehicle is righted, after having been turned over, the parts ofthe switch automatically return to their operative position.

As result of disposing the two tubes as described, several advantagesflow. The tubes can be made to contain an equal amount of mercury andthis overcomes excessive surging back and forth that would take place ina continuous V or U shaped tube. This is a fact because in either V or Ushaped tubes, the motion of the mercury, by even a slight movement ofthe vehicle, tends to become violent through inertia forces set up byits own weight notwithstanding the provision in such tubes of dampers orbaffles in an attempt to overcome this objection.

With the two tubes disposed as shown and described herein, the mercuryrests quietly in its own tube end or well. In order to start the mercuryup the tube, it would be necessary to exert considerable force and eventhen the long electrodes extending down into the tube end or well willbe washed with rising mercury forming a perfect contact even before thedeflectors 23 and surge chambers start to function as auxiliary safetyfactors.

' The mercury tubes are enclosed in the rubber cushion element in such amanner as will insure the tubes remaining in their proper position. Theyare thus protected by said elements against strain and damage. Due tothe manner in which the casing is sealed, the switch is not onlyfoolproofv but is also oil and dust-proof. Again, the switch is notaffected by normal engine operating temperature, oil, vapor, gas,moisture, climatic conditions or different altitudes.

While in describing the invention, 1'. have referred in detail to theform, arrangement and construction of the variousparts thereof, the sameis to be considered only in an illustrative sense. Hence, I do not wishto be limited to such details except as may be specifically set forth inthe appended claims.

I claim as my invention-- 1. A switch of the kind described embodyingtherein a, pair of tubes oppositely inclined from the perpendicular, aquantity of mercury normally disposed in the bottom end of each tube, apair of electrodes associated with each tube and opening thereinto toengage in the mercury in the respective tubes, a disc carried by oneelectrode of each pair above the mercury in the associated tube, andmeans connecting one electrode in each tube together, the otherelectrodes for both tubes being adapted for connection in the circuit tobe controlled.

2. A switch of the kind described embodying therein a pair of tubesoppositely inclined from the perpendicular, a quantity of mercurynormally disposed in the bottom end of each tube, a surge chamberextension on each tube and arranged at an angle thereto, a pair ofelectrodes associated with each tube and opening thereinto to' haveportions engaged in the mercury and other portions arranged in the surgechamber and means for connecting one electrode in each tube together,the other electrodes for both tubes being adapted for connection in thecircuit to be controlled.

3. A switch of the kind described embodying therein a pair of tubesoppositely inclined from the perpendicular, a quantity of mercurynormally disposed in the bottom end of each tube, a surge chamberextension on each tube and arranged at an angle thereto, a pair ofelectrodes associated with each tube and opening thereinto to haveportions engaged in the mercury and other portions arranged in the surgechamber, means in each tube and arranged to deflect the mercury therein,into the associated surge chamber extension when said tube is tippedinto that position causing the mercury to flow toward the other end ofthe tube, and means connecting one electrode in each tube together, theother electrodes for both tubes being adapted for connection in anassociated circuit.

4. A switch of the kind described embodying therein a pair of tubesoppositely inclined from the perpendicular, a quantity of mercurynormally disposed in the bottom end of each tube, a pair of electrodesassociated with each tube and having one end normally disposed in themercury in the associated tube and having the other end opening througha portion of the associated tube, a disc carried by one electrode ofeach pair above the mercury in the associated tube, and means connectingone electrode in each tube together, the other electrodes of both tubesbeing adapted for connection in the circuit to be controlled.

5. A switch of the kind described embodying therein. a pair of tubesoppositely inclined from the perpendicular, a quantity of mercurynormally disposed in the bottom end of each tube, a surge chamberextension on each tube and arranged at an angle thereto, a pair ofelectrodes extending through each surge chamber extension and into thebottom end of the associated tube so as to be disposed in themercury.therein, and means connecting one electrode in each surgechamber extension together, the other electrodes of both tubes openingthrough said extensions and being. adapted for connection in anassociated circuit.

6. A switch of the kind described embodying therein a pair of tubesoppositely inclined from the perpendicular, a quantity of mercurynormally disposed in the bottom end of each tube, a substantiallyperpendicular surge chamber extension on each tube, a pair of electrodesextending through each surge chamber extension and into the bottom endof the associated tube so as to be disposed in the mercury therein, andmeans connecting one electrode in each surge chamber extension together,the other electrodes of both tubes opening through said extensions andbeing adapted for connection in an associated circuit.

7. A switch of the kind described embodying therein a pair of tubesopositely inclined from the perpendicular, a quantity of mercurynormally disposed in the bottom end of each tube, a surge chamberextension on each tube and arranged at an angle thereto, a pair ofelectrodes extending through each surge chamber extension and into thebottom end of the associated tube so as to be disposed in the mercurytherein, means in each tube and arranged to deflect the mercury thereininto the associated surge chamber extension when said tube is tippedinto that position causing the mercury to flow toward the other end ofthe tube, and means connecting one electrode in each surge chamberextension together, the other electrodes opening through said extensionsand being adapted for connection in an associated circuit.

8. A switch of the kind described embodying therein a pair of tubesoppositely inclined from the perpendicular, a quantity of mercurynormally disposed in the bottom end of each tube, a surge chamberextension on each tube and arranged at an angle thereto, a pair ofelectrodes extending through each surge chamber extension and into thebottom end of the associated tube so as to be disposed in the mercurytherein, means secured to one electrode in each tube near said surgechamber extension and arranged to deflect the mercury in said tube intosaid surge chamber extension when said tube is tipped into that positioncausing the mercury to flow toward the other end of the tube, and meansconnecting one electrode in each surge chamber extension together, theother electrodes opening through said extensions and being adapted forconnection in an associated circuit.

9. A switch of the kind described embodying therein a pair of tubesoppositely inclined from the perpendicular, a quantity of mercurynormally disposed in the bottom end of each tube, a plurality ofconductors associated with said tubes, one of said conductors havingportions disposed in the mercury in both tubes, the other conductorseach having a portion arranged outside of an associated tube and eachhaving another portion arranged in the mercury in an asso- ,ciated tubeso that said conductors are normally connected in series through saidmercury, and a disc carried by one of said conductor portions in eachtube above the mercury therein.

EDWARD D. LAWSON.

